As I recall hearing it, it was 1 *summer*/inch. Which to me means 3
hot, dry months per inch. So, if you're in the desert southwest that's
closer to 9 months. Here in southeastern PA, where summer consists of
days on end of 90+% humidity, probably longer.

Another option is forced drying. The June issue of Woodwork
(http://woodwork-mag.com/) has an article on forced drying using a home
made kiln consisting of a plywood box and a dehumidifier. They took
wood from 24% moisture to 11% in 4 days.

dcm